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