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