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