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