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