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