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