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