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