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