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