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