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