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