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