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