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