Within the settings section of the Save to CRM add-in, you can choose which Outlook category saved emails are allocated against. This setting will default to the Yellow category, but you can type over this to choose a different category in Outlook. 

To start categorising your saved emails, click the settings toggle within Outlook.

Here, you can enable the 'Set email category' option and this will start categorising any saved emails as Yellow category.

Alternatively, you can change the default category by typing in the required Outlook category.  For example 'Blue category'. Once happy with your changes, click Close. 

Your saved emails will then be saved into the defined category. In the example below, this saved email has been put into the Yellow category within Outlook.