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