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