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