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