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