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