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