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)(11,15)(12,13)(14,16)(17,18,20,21)(19,22,23,24)(26,30)(28,36)(31,33)(34,40)(2,5)(6,8)(9,11)(10,14)(12,15)(13,16)(18,21)(19,23)(25,26,29,30)(27,33,35,31)(28,37,36,32)(34,38,40,39)(3,7)(6,8)(11,16)(14,15)(17,18,20,21)(19,22,23,24)(25,26)(27,31)(28,32)(29,30)(33,35)(34,38)(36,37)(39,40)(1,3)(2,6)(4,7)(5,8)(9,11)(10,15)(12,14)(13,16)(17,18)(19,22)(20,21)(23,24)(25,27,29,35)(26,31,30,33)(28,34,36,40)(32,38,37,39)(1,2)(3,6)(4,5)(7,8)(9,12,13,10)(11,14,16,15)(17,19,20,23)(18,22,21,24)(25,28,29,36)(26,32,30,37)(27,34,35,40)(31,38,33,39)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.