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