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)(13,14)(15,23)(16,25)(17,19)(18,26)(20,21)(22,24)(27,28) involution — undirected(1,2,4,3)(5,6)(7,10)(8,9)(11,12)(14,19)(15,21)(16,20)(18,24)(23,27)(25,28)(6,9)(10,11)(13,15,24,28,17,25,18,21)(14,20,26,16,19,27,22,23)(5,7,8,12)(6,10,9,11)(13,16,18,20,17,23,24,27)(14,21,22,25,19,28,26,15)(1,3,4,2)(14,19)(16,23)(20,27)(22,26)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.