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)(12,13)(14,15)(17,18,22,23)(19,24,21,20)(26,27)(31,33)(32,34)(38,39)(9,11)(10,13)(12,14)(15,16)(17,19)(18,20)(21,22)(23,24)(25,26,30,27)(28,33,36,31)(29,34,37,32)(35,38,40,39)(11,12)(13,16)(18,23)(19,21)(25,27,30,26)(28,33,36,31)(29,32,37,34)(35,38,40,39)(1,2)(3,5)(4,6)(7,8)(9,12,14,11)(10,13,15,16)(17,20,22,24)(18,19,23,21)(25,28,30,36)(26,31,27,33)(29,35,37,40)(32,38,34,39)(1,3,4,7)(2,5,6,8)(9,13)(10,11)(12,15)(14,16)(17,21,22,19)(18,24,23,20)(25,29,30,37)(26,32,27,34)(28,35,36,40)(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.