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