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