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