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