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