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