To change the color of the background for the CloudBooking you will need to manually change the html by following the directions below.

Here is an example CloudBooking html that is generated from the StudioCloud program. The html code below is only an example. You will need to open StudioCloud to get your actual html code.
<iframe src='http://bookingcloud.net/customName' width='445' height='289' frameborder='no'></iframe>

Here is a version that changes the text color. Notice the addition of the bc (background color) field. This field will change the color.

Here is how to change the color to white.
<iframe src='https://http://bookingcloud.net/customName?bc=FFFFFF' width='445' height='289' frameborder='no'></iframe>

Here is how to change the color to grey.
<iframe src='https://http://bookingcloud.net/customName?bc=948E8F' width='445' height='289' frameborder='no'></iframe>

Here is how to change the color to red.
<iframe src='https://http://bookingcloud.net/customName?bc=FA001E' width='445' height='289' frameborder='no'></iframe>

Here is how to change the color to blue.
<iframe src='https://http://bookingcloud.net/customName?bc=0085FA' width='445' height='289' frameborder='no'></iframe>

To select a color go to this page. 
http://www.colorpicker.com/
And select the desired color. Then copy and paste the letters and numbers in the # text box into the bc field.

For more advanced contact us modules refer to the StudioCloud Platform.