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