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