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