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