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