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