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