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)(15,22)(21,27)(24,28) involution — undirected(5,7,8,12)(6,9,10,11)(13,14)(15,23)(16,21)(17,24)(18,20)(19,27)(22,25)(26,28)(1,2,3,4)(13,15)(14,17)(16,24)(18,22)(19,28)(20,26)(21,25)(23,27)(6,10)(9,11)(13,16,18,19)(14,21,20,27)(15,24,22,28)(17,25,26,23)(7,12)(9,11)(13,17,18,26)(14,22,20,15)(16,23,19,25)(21,24,27,28)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.