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