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