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