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