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