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