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