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