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