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