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