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