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