Where is the color wheel located?
How do I change hue/saturation/value of a color in a swatch?
PyxelEdit has no color wheel nor HSV spectrum, only HSL and RGBA are available in the color window.
You can change the hue, saturation or lightness of a swatch by right-clicking on the color you want to change and choose "adjust swatch", then use the sliders for the color boxes.
You can also try out the shading panel which is available by clicking on the '>' sign.