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