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