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)(25,26,28,32,29,33,36,31)(27,30,35,39,34,38,40,37)(2,5)(6,8)(9,11,12,15)(10,13,14,16)(17,19,20,23)(18,21,22,24)(25,27)(26,30)(28,35)(29,34)(31,37)(32,39)(33,38)(36,40)(1,3)(2,6)(4,7)(5,8)(11,15)(13,16)(26,31)(28,36)(30,37)(32,33)(35,40)(38,39) involution — undirected(3,7)(6,8)(18,22)(21,24)(27,34)(30,38)(35,40)(37,39) 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.