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