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