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