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