A triple bond involving carbon should be drawn linearly. In general, if there are multiple consecutive atoms in a molecule which have a linear geometry, they should be drawn linearly. This is the case for the C–C≡C–C unit in an alkyne.
According to Graphical Representation Standards for Chemical Structure Diagrams (IUPAC Recommendations 2008):
Atoms that are isoelectronic with carbon and bearing two double bonds (or one single bond and one triple bond) should be drawn with the bonds separated by a 180° angle.
This includes carbon itself, of course. Some examples are given, including:
Note the 180° angles at the nitrile carbon (on the left), as well as both the carbon and nitrogen (on the right). Furthermore:
Large rings that contain triple bonds should depict the triple bonds in a linear fashion, just as they would be depicted in an acyclic diagram.