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