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