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)(11,18)(12,25,29,17)(13,30)(14,20)(15,21)(16,23)(19,31)(22,37,39,34)(24,33)(26,32,38,40)(27,35,28,36)(1,3,5,4)(2,6,7,8)(9,11,14,23,15,24,31,13)(10,16,19,18,21,30,20,33)(12,26,28,39,29,38,27,22)(17,34,36,32,25,37,35,40)(1,4,5,3)(2,6,7,8)(9,12,14,27,15,29,31,28)(10,17,19,35,21,25,20,36)(11,22,23,38,24,39,13,26)(16,32,18,34,30,40,33,37)(2,7)(6,8)(9,13,31,24,15,23,14,11)(10,18,20,16,21,33,19,30)(12,26,28,39,29,38,27,22)(17,34,36,32,25,37,35,40)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.