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)(13,20)(14,26)(16,28)(17,29)(18,25)(21,31)(22,32)(23,38)(24,35)(27,36)(30,40)(33,34)(37,39) involution — undirected(1,3)(2,5)(4,8)(6,7)(9,10,15,12)(11,16,22,21)(13,17,27,24)(14,18,26,25)(19,28,32,31)(20,29,36,35)(23,30,33,37)(34,39,38,40)(9,11,20,34,14,23,27,32,15,22,36,38,26,33,13,19)(10,16,29,39,18,30,24,31,12,21,35,40,25,37,17,28)(3,8)(5,7)(9,12,15,10)(11,21,22,16)(13,24,27,17)(14,25,26,18)(19,31,32,28)(20,35,36,29)(23,37,33,30)(34,40,38,39)(2,6)(5,7)(10,12)(11,22)(17,24)(18,25)(19,32)(23,33)(29,35)(34,38) 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.