In hindsight… possibly (but untested as of yet - EDIT tested below) like this…
Blynk.setProperty(vPin, "onColor", "#D3435C"); // or "onBackColor" "offColor" "offBackColor"
In hindsight… possibly (but untested as of yet - EDIT tested below) like this…
Blynk.setProperty(vPin, "onColor", "#D3435C"); // or "onBackColor" "offColor" "offBackColor"