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