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