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