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