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