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