Short Answer
The opposing sides in the Darfur conflict are all at least nominally Sunni Muslim and would all be considered by people in the U.S. or Latin America to be "black".
But, it is a conflict in which people who self-identify as Arab Muslim seek to exterminate people belonging to each of several ethnicities who self-identify as African, and the two sides view themselves as racially distinct. Since it seeks extermination of an ethnicity, it is indeed a form of genocide.
The two sides are also linguistically distinct, with one side speaking the Sudanese dialect of Arabic, and the other side broken up between several ethic groups who speak different languages, none of which are a dialect of Arabic. There are also probably differences in how the sides practice Sunni Islam that would seem minor to an outsider but are important to the parties.
Long Answer
"The Darfur genocide is the systematic killing of ethnic Darfuri people which has occurred during the ongoing conflict in Western Sudan."
"Genocide" is the deliberate killing of a large number of people from a particular nation or ethnic group with the aim of destroying that nation or group (according to Oxford Languages).
Darfur is split into two: "those who claim Black 'African' descent and
primarily practice sedentary agriculture, and those who claim 'Arab'
descent and are mostly semi-nomadic livestock herders".
While Christians and animists are predominant among sedentary farmers in most of sub-Saharan Africa, this is not true in Darfur, where both Christians and animists are scarce.
If one really wanted to be precise, one would say that the Darfur genocide is one with multiple targets with the aggressors being self-identified Arab-Muslims (in the same vein, the Holocaust in Europe, which is often considered the "type case" for what a genocide is, had multiple targets such as both Jews and Gypsies).
The main targets of the Darfur genocide are the the Fur, Masalit and Zaghawa tribes. Linguistically these belong the Furan, Maban, and Saharan language families and are commonly grouped together (along with several other language families) as Nilo-Saharan. This is in contrast to the Sudanese Arabic language of the perpetrators of the Darfur genocide, which is part of the Semitic branch (which also includes Hebrew) of the Afro-Asiatic language family.
All of the groups that are the core target of the genocide in Darfur are at least nominally Sunni Muslim, just as the aggressors are, although the "tyranny of small differences" often elevates small differences between peoples with many broad brush similarities to life and death importance, and slight differences in Islamic practice probably play some part in the antipathy present in the conflict.
Christian-animists targeted at one point are mostly in the newly formed nation of South Sudan, in a neighboring, but arguably related, conflict.
Also, while there is a difference in perceived racial identity, from the view of a typical American, both a typical Janjaweed forces member carrying out the genocide:
and a typical member of one of the tribes who have been targeted:
would both be considered "black" racially, even though someone familiar with the peoples of the area could mostly make some phenotypic distinctions between the groups, that would be fairly accurate, based upon differences between them in appearance. But, the magnitude of these fairly subtle differences might be better compared to the differences between a Greek person and a German person, both of whom would be considered "white" in the United States. The people involved in the conflict, however, would consider the differences between the conflicting sides to be racial in nature.
Simply put, there are very few people who live in Sudan who are involved in this conflict, who would be considered "white" by an American or Latin American observer. Neither side in the conflict has many participants who look like the most familiar Arab Muslims, Saudi Arabians, who often look like this:
Even linguistically, the Arabic macro-language has very diverse dialects (arguably better described as topolects), some of which differ almost as much from each other as the Romance languages do from each other. So, for example, an "Arab" Janjaweed militia member who would usually speak a Sudanese dialect of Arabic and would struggle to understand the dialect of Arabic spoken by natives of Riyadh, Saudi Arabia.
Is it accurate to frame the ongoing atrocities in Darfur as
perpetrated by Arab Muslims again Black Christians and Animists?
No. Almost all of the groups against which it has been perpetrated in Darfur are also Sunni Muslims. But, the aggressors do identify as Arab Muslim and that identity is central to the conflict:
The proxy wars between Sudan, Libya and Chad added an element of
political instability. Darfurians, mainly those who self-identified as
"Arab" and "African" people, began to respond to the ideology of Arab
supremacy propagated by Libyan leader Muammar al-Gaddafi (in power
1969-2011). A famine in the mid-1980s disrupted many societal
structures and led to the first significant modern fighting amongst
Darfuris. A low-level conflict continued for the next fifteen years,
with the government co-opting and arming Arab Janjaweed militias
against its enemies.
