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