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