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