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