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