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