In Camunda 8 and Modeler 5.0 you can add custom graphics to entities in Element Templates Scalable Vector Graphics (SVG) are ideal since they are vector rather than raster diagrams. SVGs are infinitely scalable and do not lose their original fidelity. Now available in the Community Hub is a library of ready to use icons along with converters to take just about any (though the simpler the better) SVG and convert it for use in an Element Template. Enjoy!
https://github.com/camunda-community-hub/element-template-svg-converter
Joe