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