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