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