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