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