You’d want to use the call service node with domain, light and service lifx_set_state
I’ll edit this with an example flow when I can get chance
Here’s a flow using my wink relay to set light colors:
[{"id":"57621e37.8c862","type":"mqtt in","z":"7a198d74.f39644","name":"Bedroom 1 Hold","topic":"wink_bedroom/buttons/1/held/1","qos":"2","broker":"dc770962.2c27d8","x":340,"y":40,"wires":[["8b14aba2.f8a9c8","8edf329a.91e8b","571a30dd.b9b73"]]},{"id":"571a30dd.b9b73","type":"api-call-service","z":"7a198d74.f39644","name":"Floor Lamp Blue","server":"dd768228.85ca3","service_domain":"light","service":"lifx_set_state","data":"{ \"entity_id\":\"light.lamp\", \"power\":\"true\", \"brightness\":\"255\", \"rgb_color\":[0, 0, 255] }","mergecontext":"","x":600,"y":40,"wires":[[]]},{"id":"8edf329a.91e8b","type":"api-call-service","z":"7a198d74.f39644","name":"Fan Purp","server":"dd768228.85ca3","service_domain":"light","service":"lifx_set_state","data":"{ \"entity_id\":\"light.fan\", \"power\":\"true\", \"brightness\":\"255\", \"rgb_color\":[148, 0, 211] }","mergecontext":"","x":580,"y":80,"wires":[[]]},{"id":"8b14aba2.f8a9c8","type":"api-call-service","z":"7a198d74.f39644","name":"Lamp Pink","server":"dd768228.85ca3","service_domain":"light","service":"lifx_set_state","data":"{ \"entity_id\":\"light.bedside_lamp\", \"power\":\"true\", \"brightness\":\"255\", \"rgb_color\":[249, 2, 142] }","mergecontext":"","x":590,"y":160,"wires":[[]]}]