Graph[{{{1, 3}}, {{2, 3}}}, {{{0, 0}, VertexColor -> RGBColor[0., 0., 1.]}, 
  {{0, 1}, VertexColor -> RGBColor[0., 0., 1.]}, 
  {{1, 0}, VertexColor -> RGBColor[0., 0., 1.]}}]
