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