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