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