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