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