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