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