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