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