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