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