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