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