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)(11,21)(12,19)(13,16)(14,17)(15,20)(18,22)(23,24)(25,26,28,32,29,33,37,31)(27,30,36,39,35,38,34,40)(1,3,4,7)(2,5,6,8)(9,11,12,23,15,22,14,13)(10,16,17,18,20,24,19,21)(25,27,28,36,29,35,37,34)(26,30,32,39,33,38,31,40)(2,6)(5,8)(9,12,15,14)(10,17,20,19)(11,13,22,23)(16,21,24,18)(26,31)(27,34)(28,37)(30,38)(32,33)(35,36)(9,13,14,22,15,23,12,11)(10,18,19,16,20,21,17,24)(27,35)(30,38)(34,36)(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.