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