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