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