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