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