FOR CUSTOM LAYOUTS
You can select colorful or neutral grey in the Design Center, there is a tab on the left side labeled DATE. This is the tab you open to select COLORFUL or NEUTRAL GREY
Above example shows the Neutral Grey option selected. If you notice, the text for the Month and Weekdays are in neutral grey/black text.
A colorful layout will display the Month and Dates in different colors for each month.
A neutral grey layout will display the Month and Dates as neutral grey/black.
FOR NON-CUSTOM/STANDARD LAYOUTS
You can select colorful or neutral grey in Step 2 Inside Pages (not in the Design Center). Step 2 Inside Pages is where you’ll select either COLORFUL or NEUTRAL GREY.
If you select colorful, then the layout design will appear in different colors for each month.
If you select neutral grey, the layout will appear in a consistent black/white/neutral grey coloring throughout every page.