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