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