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