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