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