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