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