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