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