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