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