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