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