One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,5)(3,6,7,8)(9,10,12,13)(11,14,15,16)(17,18,20,22)(19,21,23,24)(25,26,31,37)(27,38,40,34)(28,33,39,32)(29,36,30,35)(2,5)(6,8)(17,19)(18,21)(20,23)(22,24)(25,27,30,28,31,40,29,39)(26,32,36,34,37,33,35,38)(1,3,4,7)(2,6,5,8)(10,13)(14,16)(19,23)(21,24)(25,27,29,39,31,40,30,28)(26,33,35,34,37,32,36,38)(9,11,12,15)(10,14,13,16)(25,28,30,40,31,39,29,27)(26,34,36,33,37,38,35,32)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.