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