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