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