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