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