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