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