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