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