When you drag a View into a Layout, it becomes a Drawing and has specific settings available to set how it will look on that sheet. One of the settings is the Pen Set; you can set it to use the Original Pen Set or override it to use a different one.
It is common for people to work in color on their model, but change the pen set for the Drawing to make some or all of the pens black instead of in color.
By the way, if you change the active Pen Set in the Layout Book using the Document menu, you'll only affect elements drawn directly onto the Layout or the Master; you won't affect the Drawings on the Layout (which each have their own Drawing Settings which include the Pen Set as described above).
As a side note, when you drag a View onto a Layout it will use the Default Drawing Settings (which allows you to set a standard for how drawings will look on your sheets). If it's set to use a different Pen Set than what you want, then you can open up the Drawing Setting dialog when nothing is selected, and change it; this will affect the Default for new Drawings. You can also eye-drop a Drawing to pick up the settings for the Default, although you have to be careful not to lock in other settings that should be variable (for example, if the drawing you are eye-dropping has a manually set Title, then the default would have the same Title, rather than the more common and useful Title set to match the Original View).