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