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