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