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