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