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