I have an OpenMRS installation. I installed it on my local system. I have not been able to find an appropriate module or way to customize it. Let's say change the logo and default color.
Any suggestions?
Your question is unclear, but I'll assume you're referring to the latest OpenMRS 2 product rather than the older/simpler Platform product.
The style guide at http://demo.openmrs.org/openmrs/uicommons/styleGuide.page#override suggests adding a file called customVariables.scss with the colors, etc., you wish to override.
For the older Platform product, a quick Google search shows there is a "Custom Branding Module" at https://wiki.openmrs.org/display/docs/Custom+Branding+Module that looks like it might do what you want.
OpenMRS is not really a consumer product and has a relatively small number of users, so you probably won't get many answers here on SO. You'll probably be more successful if you use the project's Q&A site or forums if you don't get any more detailed answers.
Good luck!