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