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