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