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