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