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