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