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