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)(15,18)(16,17)(19,20)(23,27)(26,28) involution — undirected(2,4)(5,6,9,8)(7,10,11,12)(14,17)(18,19)(22,25)(26,28)(1,2,3,4)(6,8)(10,12)(13,14)(15,19)(16,17)(18,20)(21,22)(23,26)(24,25)(27,28)(5,7,9,11)(6,10,8,12)(13,14)(15,19)(16,17)(18,20)(21,23)(22,26)(24,27)(25,28)(5,8,9,6)(7,10,11,12)(13,15,16,20)(14,18,17,19)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.