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