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