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