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