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