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