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