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