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