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