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)(11,14)(12,13)(15,16)(17,18,21,24)(19,22,20,23)(25,26)(27,31)(28,30)(29,36)(32,38)(33,40)(34,35)(37,39)(1,3,5,8)(2,4,6,7)(9,11)(10,14)(12,15)(13,16)(26,28)(31,35)(32,36)(39,40)(2,6)(4,7)(9,11,13,16)(10,15,12,14)(17,19,21,20)(18,22,24,23)(25,27,30,34)(26,31,28,35)(29,37,38,33)(32,40,36,39)(1,3)(2,4)(5,8)(6,7)(9,11)(10,15)(12,14)(13,16)(17,18)(19,22)(20,23)(21,24)(25,28,30,26)(27,31,34,35)(29,36,38,32)(33,39,37,40)(1,4)(2,3)(5,7)(6,8)(9,12,13,10)(11,14,16,15)(17,20,21,19)(18,23,24,22)(25,29,30,38)(26,32,28,36)(27,33,34,37)(31,39,35,40)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.