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