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