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)(15,20)(16,22)(17,23)(18,27)(19,24)(21,25)(26,28) involution — undirected(1,2)(3,4)(5,7)(6,10)(8,11)(9,12)(13,15)(14,20)(16,18)(17,26)(19,25)(21,24)(22,27)(23,28) involution — undirected(2,4)(13,16,19,26)(14,21,24,20)(15,17,25,18)(22,23,28,27)(6,11)(7,12)(13,15)(14,22)(16,17)(18,26)(19,25)(20,27)(21,23)(24,28) involution — undirected(5,8,9,10)(6,7,11,12)(13,17,19,18)(14,23,24,27)(15,16,25,26)(20,22,21,28)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.