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