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