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