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)(15,19)(16,21)(17,20)(18,22)(23,26)(24,28)(25,27) involution — undirected(1,2)(3,4)(5,7)(6,10)(8,11)(9,12)(13,15,18,24)(14,19,22,28)(16,25,17,23)(20,26,21,27)(2,4)(14,20)(16,17)(19,26)(21,22)(23,25)(27,28) involution — undirected(6,11)(7,12)(14,20)(16,17)(19,26)(21,22)(23,25)(27,28) involution — undirected(5,8,9,10)(6,7,11,12)(13,16,18,17)(14,21,22,20)(15,23,24,25)(19,26,28,27)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.