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