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