Drawing charts and plots in C++ without GUI library can be challenging, but it's not impossible. You can use system API (like WinAPI) or third-party drawing libraries. With GUI library (especially Qt) it's much easier as you have in this situation portable window handling and painting device already provided.
Below you can find collection of free or low-cost resources for C/C++.
- Voronoi diagram
- Dragon curve
- Visual C++ - Ploting Trigonometric Functions Graph - Sin, Cos and Tan Series
- QCustomPlot - for Qt
- Qt Data Visualization - 3D charts, part of Qt
- Qwt - Qt widgets for technical applications