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