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