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