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