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