Thought this turned out too bright, find subtle quite difficult!
Totally agree the colour is a bit too bright.
You could try mixing white acrylic or gouache into your colours. They are body paints so are opaque. Or you could mix a grey or brown into your colours to mute them.
Try playing about with your colour settings on the photo. Adjust one of the colours and see what would have happened if you'd have mixed that colour into all your colour mixed.