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