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