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