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