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