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