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