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