This bpmn-js extension adds a simple color picker to an elements context pad. Colors are serialized to BPMN 2.0 according to the BPMN in Color proposal.

bpmn-js@8.7+)Fetch bpmn-js-color-picker as a dependency:
npm install bpmn-js-color-picker --save
Extend your BPMN modeler with colors:
import BpmnModeler from 'bpmn-js/lib/Modeler';
import BpmnColorPickerModule from 'bpmn-js-color-picker';
const modeler = new BpmnModeler({
additionalModules: [
BpmnColorPickerModule
]
});
Add diagram-js, bpmn-font and color picker stylesheets:
<link rel="stylesheet" href="https://unpkg.com/bpmn-js/dist/assets/diagram-js.css" />
<link rel="stylesheet" href="https://unpkg.com/bpmn-js/dist/assets/bpmn-font/css/bpmn-embedded.css" />
<link rel="stylesheet" href="https://unpkg.com/bpmn-js-color-picker/colors/color-picker.css" />
To run the live demo in the ./example directory (as shown in the screenshot above) execute:
npm start
$ claude mcp add bpmn-js-color-picker \
-- python -m otcore.mcp_server <graph>