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