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