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