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