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