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