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