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