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