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