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