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