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