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