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