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