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