You can use this flow. It works for me in testing.
If you dont want 100% Saturation, just change the value or you can also make it dynamic based on a different msg.
[{"id":"f3a8d56cc593d90d","type":"inject","z":"5c5d6708.65ab48","name":"","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"40","payloadType":"num","x":150,"y":800,"wires":[["83e8db7f2219e39f"]]},{"id":"83e8db7f2219e39f","type":"function","z":"5c5d6708.65ab48","name":"Payload to HS_Color","func":"newmsg = {}\n\nnewmsg.payload = { data: { \"hs_color\":[msg.payload, 100]} }\n\nreturn newmsg;\n","outputs":1,"noerr":1,"initialize":"","finalize":"","libs":[],"x":400,"y":800,"wires":[["9553885803764f31","e3d1bb2346f4d73b"]]},{"id":"e3d1bb2346f4d73b","type":"debug","z":"5c5d6708.65ab48","name":"debug 5","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":700,"y":800,"wires":[]},{"id":"9553885803764f31","type":"api-call-service","z":"5c5d6708.65ab48","name":"","server":"","version":5,"debugenabled":false,"domain":"light","service":"turn_on","areaId":[],"deviceId":["f6354e1a4d3e0310afcbda4601ada4fa"],"entityId":[],"data":"","dataType":"jsonata","mergeContext":"","mustacheAltTags":false,"outputProperties":[],"queue":"none","x":510,"y":900,"wires":[["e3d1bb2346f4d73b"]]}]
Scrubbed via: Scrubber | node-red-contrib-home-assistant-websocket