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