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