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