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