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