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