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)(27,34)(28,32)(29,37)(30,33)(31,35)(36,39)(38,40) 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)(28,29)(32,37)(34,39)(35,38)(1,3)(2,5)(4,7)(6,8)(9,11,14,20)(10,16,18,23)(12,21,13,19)(15,22,17,24)(25,27)(26,31)(28,35)(29,38)(30,36)(32,39)(33,40)(34,37)(9,12,14,13)(10,17,18,15)(11,19,20,21)(16,22,23,24)(25,28,30,29)(26,32,33,37)(27,35,36,38)(31,39,40,34)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.