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