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