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