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