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