As usual: IANAL, but I'd say that...
Yes: you can copy UI elements and color-schemes
Elements of UI Design are NOT Generally Viewed as IP
While You can patent functionalities and behaviors, you cannot patent or copyright or trademark a design, except if it's the design of a brand or logo for a registered trademark. Similarly, you can't copyright a color charter: it's too generic.
However, you can patent GUI-related functionalities, unfortunately, because the patent system is clueless (in the US and some other countries). e.g., double-clicking, swiping, and things like that...
In the case of a complete clone, as far as I know (which isn't much, let's make that clear again), this could be ground for legal issues. Meaning if you'd have copied the screen's content, mode of navigation AND color schemes, some people would find it legitimate to sue you. Doesn't mean they would succeed, but that could a risk. They'd be unlikely to succeed as they can't own the IP for the design, and you'd have re-implemented it entirely.
For additional confirmation and what it's worth:
However, note that there's literature covering the other hangle as well, such as the "Appendix L - What Can You Borrow" to "Task-Centered User Interface Design":
- Things you can probably not copy -- again, watch the news and check with your attorney.
- Sequences or arrangements of menu items, commands, screens, etc., if you're only copying the sequence order because it will make it easier for users of someone else's existing program to use your new program.
- Icons, commands, menu items, or other words that are not an obvious choice to describe their function, even if they would make your program more usable for users of the original program. An example might be a database print command labelled "DataDump," or a mouse-options icon showing a cute little mouse with a checklist.
- Things you can certainly not copy (unless you get permission).
- Things you've written earlier for a different company.
- An entire interface from another company's program, even if you implement it with all new code.
- An entire detailed screen from another company's program.
- Trademarks from other companies. If you need to use someone else's trademark, such as "Unix" in documentation, be sure you credit the owner: "Unix is a trademark of Unix Systems Laboratories, Inc."
- Patented features. Unfortunately, there's no easy way to discover what's patented.
- Exact bitmaps of icons, words, or fonts.
- Graphic details that define an interface's aesthetic look.
- this leaves room for interpretation,
- this isn't legal advice either.
Bottom Line? Get a Lawyer... or Don't Copy!!!