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