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