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