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