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