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