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