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