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