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