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