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