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