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