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