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