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