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