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