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