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