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