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