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