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