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