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