Hi,
Thank You for reaching out to us!!
Sorry but there is no such separate setting or option to change backgraound color of contact form from default blue to any other color.
We need to do certain changes in its styling to change the background color of contact form, we can do it for you, for that, you just need to make user for us, assign administrator role, and send us username and password of your WordPress site along with site URL at [email protected].
Please let us know if you need any other help with the theme.
Thanks & Best Regards