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