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