The following VBA example draws a small ellipse over each node in the selected curve and colors each ellipse according to the node type.
Sub ShowNodes()
Dim n As Node
Dim s As Shape
For Each n In ActiveShape.Curve.Nodes
Set s = ActiveLayer.CreateEllipse2(n.PositionX, n.PositionY, 0.05)
Select Case n.Type
Case cdrSymmetricalNode
s.Fill.UniformColor.RGBAssign 0, 0, 255
Case cdrSmoothNode
s.Fill.UniformColor.RGBAssign 255, 255, 0
Case cdrCuspNode
s.Fill.UniformColor.RGBAssign 255, 0, 0
End Select
Next n
End Sub