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