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