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