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