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)(25,26,28,31,29,32,35,38)(27,30,34,37,33,36,39,40)(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)(28,34)(29,33)(31,37)(32,36)(35,39)(38,40)(2,7)(6,8)(27,33)(30,36)(34,39)(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.