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