Solution
Unselect the Print in black and white option to avoid encountering this issue.
Explanation
Microsoft PowerPoint treats the driver as a black-and-white printer when the Print in black and white option is selected from outside the application.
Changing the settings to Color within the application does not affect the Print Preview since it generalizes the overall settings.
This issue is considered as an Application Limitation.
If the issue persists, then search for more information related to this issue or contact customer support.