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