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