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