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