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