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