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