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