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