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