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