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