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