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