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