ch08: Drop references to specific colors in diagram

ch08.asciidoc

@@ -18,13 +18,13 @@ Bitcoin's P2P network architecture is much more than a topology choice. Bitcoin
 .A bitcoin network node with all four functions: wallet, miner, full blockchain database, and network routing
 image::images/mbc2_0801.png["FullNodeReferenceClient_Small"]
 
-All nodes include the routing function to participate in the network and might include other functionality. All nodes validate and propagate transactions and blocks, and discover and maintain connections to peers. In the full-node example in <<full_node_reference>>, the routing function is indicated by an orange circle named "Network Routing Node" or with the letter "N."
+All nodes include the routing function to participate in the network and might include other functionality. All nodes validate and propagate transactions and blocks, and discover and maintain connections to peers. In the full-node example in <<full_node_reference>>, the routing function is indicated by a circle named "Network Routing Node" or with the letter "N."
 
 ((("full-node clients")))Some nodes, called full nodes, also maintain a complete and up-to-date copy of the blockchain. Full nodes can autonomously and authoritatively verify any transaction without external reference. ((("simple-payment-verification (SPV)")))Some nodes maintain only a subset of the blockchain and verify transactions using a method called _simplified payment verification_, or SPV. ((("lightweight clients")))These nodes are known as SPV nodes or lightweight nodes. In the full-node example in the figure, the full-node blockchain database function is indicated by a circle called "Full Blockchain" or the letter "B." In <<bitcoin_network>>, SPV nodes are drawn without the "B" circle, showing that they do not have a full copy of the blockchain.
 
-((("bitcoin nodes", "mining nodes")))((("mining and consensus", "mining nodes")))((("Proof-of-Work algorithm")))((("mining and consensus", "Proof-of-Work algorithm")))Mining nodes compete to create new blocks by running specialized hardware to solve the Proof-of-Work algorithm. Some mining nodes are also full nodes, maintaining a full copy of the blockchain, while others are lightweight nodes participating in pool mining and depending on a pool server to maintain a full node. The mining function is shown in the full node as a black circle called "Miner" or the letter  "M."
+((("bitcoin nodes", "mining nodes")))((("mining and consensus", "mining nodes")))((("Proof-of-Work algorithm")))((("mining and consensus", "Proof-of-Work algorithm")))Mining nodes compete to create new blocks by running specialized hardware to solve the Proof-of-Work algorithm. Some mining nodes are also full nodes, maintaining a full copy of the blockchain, while others are lightweight nodes participating in pool mining and depending on a pool server to maintain a full node. The mining function is shown in the full node as a circle called "Miner" or the letter  "M."
 
-User wallets might be part of a full node, as is usually the case with desktop bitcoin clients. Increasingly, many user wallets, especially those running on resource-constrained devices such as smartphones, are SPV nodes. The wallet function is shown in <<full_node_reference>> as a green circle called "Wallet" or the letter "W."
+User wallets might be part of a full node, as is usually the case with desktop bitcoin clients. Increasingly, many user wallets, especially those running on resource-constrained devices such as smartphones, are SPV nodes. The wallet function is shown in <<full_node_reference>> as a circle called "Wallet" or the letter "W."
 
 In addition to the main node types on the bitcoin P2P protocol, there are servers and nodes running other protocols, such as specialized mining pool protocols and lightweight client-access protocols.