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