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