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