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