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)(14,20)(15,25)(17,18)(21,26)(22,28)(23,24) involution — undirected(5,7)(6,9)(8,11)(10,12)(13,14,17,23,19,24,18,20)(15,26,28,27,22,21,25,16)(2,4)(7,11)(9,12)(13,15,18,25,19,22,17,28)(14,21,20,27,24,26,23,16)(7,11)(9,12)(13,16,19,27)(14,22,24,15)(17,26,18,21)(20,28,23,25)(6,10)(9,12)(13,17,19,18)(14,23,24,20)(15,25,22,28)(16,21,27,26)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.