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