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) involution — undirected(1,2,3,4)(6,9)(7,12)(14,16)(18,19)(22,25)(26,28)(13,14,17,16)(15,18,20,19)(21,22,24,25)(23,26,27,28)(5,7)(6,10)(8,12)(9,11)(13,15)(14,18)(16,19)(17,20)(21,23,24,27)(22,26,25,28)(5,6)(7,10)(8,9)(11,12)(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.