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)(14,15)(16,20)(22,24)(26,27) involution — undirected(5,6,9,8)(7,10,12,11)(13,14,17,15)(16,18,20,19)(21,22)(23,27)(24,25)(26,28)(6,8)(10,11)(13,14,17,15)(16,19,20,18)(21,23,25,28)(22,26,24,27)(1,2,3,4)(5,7)(6,10)(8,11)(9,12)(13,15,17,14)(16,18,20,19)(21,24,25,22)(23,27,28,26)(5,8,9,6)(7,10,12,11)(13,16)(14,18)(15,19)(17,20)(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.