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