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