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