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