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