I think this is the standard for the Oryctini and has keys to genera and species:
ENDRODI, S. 1985. The Dynastinae of the World. Dr. W. Junk Publisher, Dordrecht. If you're stuck, maybe you could contact someone involved in this project (http://museum.unl.edu/research/entomology/Guide/Guide-introduction/Guideintro.html) or Darren Mann here (http://www.oum.ox.ac.uk/collect/lifecoll1.htm) - hope that helps.