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