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