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