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