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)(11,12)(13,15)(14,16)(20,24)(22,23)(25,26,30,31)(27,28,33,36)(29,32,38,39)(34,35,37,40)(2,6)(3,8)(9,11,14,13)(10,15,16,12)(17,18,21,19)(20,22,24,23)(26,31)(27,33)(32,39)(34,37)(2,6)(4,7)(10,16)(11,13)(17,19,21,18)(20,23,24,22)(25,27)(26,28)(29,37)(30,33)(31,36)(32,40)(34,38)(35,39)(1,3,5,8)(2,7,6,4)(9,12,14,15)(10,11,16,13)(17,20,21,24)(18,22,19,23)(25,28)(26,27)(29,35)(30,36)(31,33)(32,34)(37,39)(38,40)(1,4,5,7)(2,8,6,3)(9,13,14,11)(10,15,16,12)(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.