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