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