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