White is probably the most traditional color for a "farmhouse" but there are other schemes that will also work. Here are some examples from houzz...

Beige

[Farmhouse Exterior[(https://www.houzz.com/photos/farmhouse-exterior-home-ideas-phbr1-bp~t_736~s_2114) by Perkasie Design-Build Firms David Brooke Rush Builders

red

[Farmhouse Exterior[(https://www.houzz.com/photos/farmhouse-exterior-home-ideas-phbr1-bp~t_736~s_2114) by Little Rock General Contractors Bret Franks Construction, Inc.

blue

[Farmhouse Exterior[(https://www.houzz.com/photos/farmhouse-exterior-home-ideas-phbr1-bp~t_736~s_2114) by Nashville Interior Designers & Decorators Marilyn Kimberly, Interior Designer

deep grey

[Farmhouse Exterior[(https://www.houzz.com/photos/farmhouse-exterior-home-ideas-phbr1-bp~t_736~s_2114) by Boone Architects & Building Designers Marland Architecture

You might even want to reconsider yellow...

[Farmhouse Exterior[(https://www.houzz.com/photos/farmhouse-exterior-home-ideas-phbr1-bp~t_736~s_2114) by Middlebury Interior Designers & Decorators Connor Homes

I think the most important thing with a farmhouse is to keep the color scheme simple and "sharp" looking. Often by painting the trim white. I'd definitely want the porch to be white. Hope your HOA isn't dead set against white trim too.

Maybe one of these will strike your fancy.

While I wouldn't want a yellow house, there is a soft shade of cream...a very toned down yellow...that is a lovely color.

Here is a link that might be useful: Farmhouse colors

Did they say no to "white" or *white*? (ie, can it be sandstone beige?) Natural clay seems a little dark, to me, for a farmhouse. Have you considered desert tan? The house pictured in the brochure with desert tan is a farmhouse style home...