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