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