A full list of data icons can be found under the top right menu: Edit Place, Data +, but here are the common ones used in the default setup:
Graph Colours:
Default graph 1:
Precipitation: blue
Total Cloud: grey
Wind Speed: green line
Note: yellow is sun by default i.e. no precipitation or cloud
Default graph 2:
Temperature: blue line
Delta Temp Decrease: blue shading
Delta Temp Increase: red shading
Note: Delta Temp is the comparison of temperature to the same time the previous day, which indicates if it is getting colder or warmer compared to the day before.