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