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