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