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