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