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