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)(11,14,18,22)(12,15,20,24)(17,21,19,23)(25,26,32,29)(27,37,40,34)(28,38,39,33)(30,35,31,36)(2,5)(6,8)(9,11)(10,14)(12,19)(13,18)(15,23)(16,22)(17,20)(21,24)(25,27,31,39,32,40,30,28)(26,33,35,37,29,38,36,34)(1,3,4,7)(2,6,5,8)(9,12)(10,15)(11,17)(13,20)(14,21)(16,24)(18,19)(22,23)(25,28,31,27,32,39,30,40)(26,34,35,33,29,37,36,38)(12,20)(15,24)(17,19)(21,23)(25,29,32,26)(27,38,40,33)(28,37,39,34)(30,35,31,36)(11,18)(14,22)(17,19)(21,23)(25,30,32,31)(26,35,29,36)(27,28,40,39)(33,37,38,34)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.