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