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