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