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