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