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