@KOMARINA  there is a new Troubleshooting Video which might help answer your question.

It is not clear whether you are using conditional formatting for those column colours - ie does it depend on a date or number format which you need to mimic in the export template?  Or are you using a CSS skin ?

If so please note that what you are trying to achieve is currently not possible.  See this post. this post and this post.

We did not add support to include cell style and format. It is possible to retain cell style and format from a template.

We try to discourage Pega designers from calling the activity responsible for doing Export To Excel as this causes various problems. The only supported way to use Export to Excel is by using the Export to Excel option on Report Definitions.

Please could you follow the post  How to format excel file and style according to requirement?

This link is related to excel export from Report Definition.  

For an example on the use of a Template (Binary File) see this post.

The main documentation on what is, and what is not possible with pxGenerateExcelFile  is in Activities for integrating cases with Excel documents

See the table in the document which lists features that Pega Platform supports when generating Excel files with the pxGenerateExcelFile activity:

Note that there is an open enhancement  to create a definitive document outlining the limitations and workarounds for export to Excel.