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