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