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)(25,26,31,36)(27,33,38,39)(28,32,37,40)(29,35,30,34)(1,3,5,4)(2,6,7,8)(9,11,13,12)(10,14,15,16)(17,19)(18,21)(20,23)(22,24)(25,27,29,28,31,38,30,37)(26,32,34,33,36,40,35,39)(9,12,13,11)(10,14,15,16)(19,23)(21,24)(25,27,29,28,31,38,30,37)(26,32,34,33,36,40,35,39)(1,4,5,3)(2,6,7,8)(25,28,29,38,31,37,30,27)(26,33,34,40,36,39,35,32)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.