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