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