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