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