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