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)(11,18)(12,20)(13,16)(14,17)(15,21)(19,23)(22,24)(25,26)(27,32)(28,37)(29,34)(30,31)(33,38)(35,36)(39,40) involution — undirected(2,6)(3,7)(9,11,14,16)(10,13,17,18)(12,19,21,24)(15,23,20,22)(25,26)(27,35)(28,33)(29,34)(30,31)(32,36)(37,38)(39,40)(1,3,5,7)(2,4,6,8)(12,21)(15,20)(19,24)(22,23)(26,31)(27,36)(33,37)(34,40)(1,4)(2,7)(3,6)(5,8)(9,12,14,21)(10,15,17,20)(11,19,16,24)(13,23,18,22)(25,27)(26,32)(28,34)(29,37)(30,36)(31,35)(33,39)(38,40)(9,10)(11,13)(12,15)(14,17)(16,18)(19,23)(20,21)(22,24)(25,28)(26,33)(27,34)(29,35)(30,38)(31,37)(32,39)(36,40) involution — undirected(9,13)(10,16)(11,17)(12,22)(14,18)(15,19)(20,24)(21,23)(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.