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