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