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