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