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