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