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