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