Sequence colors can be displayed in two modes: history colors (default) and custom colors.
History Colors Mode

To view history colors, open the Options dialog by clicking View → Map & Sequence Options... . Click the "Show colors" button, click the Show colors menu button, select "History Colors", then click OK.

Alternatively, click the "Show colors" menu button from the side toolbar, then click "History Colors."
View History Colors

History colors will now be shown in Map and Sequence views.
View Custom DNA Colors

To switch from displaying history colors to previously defined custom colors, open the Options dialog by clicking View → Map & Sequence Options... . Click the Show colors menu button, select "Custom DNA Colors", then click OK.

Alternatively, click the "Show colors" menu button from the side toolbar, then click "Custom DNA Colors".
View Custom DNA Colors

Customized sequence colors will now be shown in Map and Sequence views.