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