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