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