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