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