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)(15,19)(16,18)(17,20)(21,24)(22,26)(23,25)(27,28) involution — undirected(2,3)(5,7)(6,9)(8,12)(10,11)(15,22)(19,26)(23,28)(25,27) involution — undirected(1,2,4,3)(7,12)(9,11)(14,18)(16,24)(19,25)(20,21)(23,28)(26,27)(6,10)(9,11)(13,15,17,22)(14,19,20,26)(16,23,24,28)(18,25,21,27)(1,3,4,2)(14,20)(15,22)(18,21)(23,28)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.