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