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