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