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