The bottom ten tend to be obscure public schools like San Jose St., along with football-crazed powerhouses Oklahoma and Texas.
The biggest gap between football players graduation rates and all students is at UCLA (52% v. 89%) — and UCLA isn't even getting very good football players. (UCLA used to have a low graduation rate for regular students because it could take 5 or 6 years to get all the classed you needed to graduate. But I think the spread of Advanced Placement tests in high school, among other reasons, has made it easier to graduate in 4 years.)
The biggest gap between the graduation rates of white football players and black football players was at Auburn. The third biggest race gap was at Oregon. Auburn and Oregon played for the national championship in January, so maybe that's a clever strategy: recruit smart white kids and lower your standards for black athletes.