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