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