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