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