One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(6,8)(9,10,15,20)(11,21,23,33)(12,26,30,35)(13,19,14,18)(16,25,32,24)(17,28,36,29)(22,37,38,31)(27,34,39,40)(1,2,3,4)(9,11,13,24,15,23,14,25)(10,16,18,21,20,32,19,33)(12,27,28,22,30,39,29,38)(17,34,35,31,36,40,26,37)(9,12,13,29,15,30,14,28)(10,17,18,26,20,36,19,35)(11,22,24,27,23,38,25,39)(16,31,21,34,32,37,33,40)(5,6,7,8)(11,23)(16,32)(21,33)(22,38)(24,25)(27,39)(31,37)(34,40)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.